Upgrading to new LTS 20 from LTS 18 via command update-manager -d

[Simon Sundell]

Description: Ubuntu 18.04.4 LTS
Release: 18.04
Error message says
This was probably caused by:
  * Unofficial software packages not published by Ubuntu
Use the "ppa-purge" tool from the ppa-purge package
to remove software from a Launchpad PPA and
try to upgrade again.

I am trying to upgrade to new LTS using terminal command update-manager -d
I've installed ppa-purge and tried using it but I can't seem to figure out which to package to remove. I've tried looking in the logs but the issue "escapes" me
Regards, Simon

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubuntu-release-upgrader-core 1:18.04.37
ProcVersionSignature: Ubuntu 4.15.0-99.100-generic 4.15.18
Uname: Linux 4.15.0-99-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Sat May 9 18:25:31 2020
InstallationDate: Installed on 2016-06-02 (1437 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to bionic on 2020-05-09 (0 days ago)
VarLogDistupgradeTermlog:

[Brian Murray (brian-murray)]

There is a new version of the release upgrader available which may address the failure to calculate an upgrade which you encountered. Could you please try the upgrade again and report back? Thanks in advance.

[Simon Sundell (simsun1024)]

Yes, upgrading with the new version works!